(北京航空材料研究院， 北京 100095)
摘 要: 研究了Ti48Al合金全片層組織在1 150 ℃時效時的組織穩(wěn)定性。結(jié)果表明，1 400 ℃，1 h固溶處理后爐冷獲得的粗片層組織的穩(wěn)定性遠遠優(yōu)于空冷獲得的細片層組織。細片層組織首先在晶界處發(fā)生不連續(xù)粗化，而后粗化片層組織中的 α2相發(fā)生溶解并球化，從而轉(zhuǎn)變?yōu)榻?γ 組織；空冷組織中魏氏片層的存在降低了片層組織的穩(wěn)定性，魏氏片層/基體界面與晶界一同成為片層組織發(fā)生分解的起始部位。Ti48Al+0.8%B(摩爾分數(shù))合金的細片層組織因晶界TiB2相的存在有效抑制了晶界不連續(xù)粗化，但 γ 相從TiB2/基體界面和晶界重新形核生長使片層組織轉(zhuǎn)變?yōu)榫鶆虻募毦Ы?EM>γ組織。
關(guān)鍵字: TiAl合金； 片層組織；穩(wěn)定性； 不連續(xù)粗化
（Beijing Institute of Aeronautical Materials， Beijing 100095， P.R.China）
Abstract:The thermal stability of fully lamellar microstructures of Ti48Al alloy after aging at 1 150 ℃ was studied. The thermal stability of coarse lamellar microstructure produced by heattreatment at 1 400 ℃ for 1 h, followed by furnace cooling is superior to that of the fine lamellar microstructure produced by air cooling. During the aging， the discontinuous coarsening (DC) occurs at the grainboundaries of the fine lamellar microstructure， then α2 phase of the coarsened lamellar microstructures dissolves and spheroidizes. Ultimately， the fine lamellar microstructure transforms into the near gamma microstructure. The Widmanstatten lamellar colonies produced by air cooling from the α single phase field degrade the thermal stability of the fine lamellar microstructure， the decomposition of the fine lamellar microstructure initiates at the Widmanstatten lamellar/matrix interfaces and grain boundaries. The TiB2 particles at grain boundaries in Ti48Al +0.8%B (mole fraction) alloy restrain the discontinue coarsening effectively. However， the new γ grains nucleate and grow at the TiB2/matrix interfaces and grain boundaries. As a result， the fine lamellar microstructure transforms into the homogeneous and fine near gamma microstructure.
Key words: TiAl alloy； lamellar microstructure； thermal stability； discontinuous coarsening
